Conventional intravenous catheter apparatus includes a hollow syringe needle and a close-fitting surrounding sheath from which a point of the needle initially projects. The needle point and sheath are inserted into a vein so that blood back-flows through the needle into a transparent hollow push-pull element, usually cylindrical and somewhat elongated, fixed on the needle remote from its point. The appearance of blood within that transparent element indicates that the needle and sheath have been properly inserted in the vein. Typically there is a cylindrical elongated vial coaxially located on the end of the sheath and the needle initially extends coaxially through a circular end opening in the vial and through the sheath. After proper insertion in the vein the needle is then withdrawn from the sheath and from the vial through the opening in the vial and is discarded. The end of a flexible tube is then fitted into the vial opening to communicate with a source of intravenous fluid.
It is common in this prior art method of intravenous injection to experience leakage of blood between the time that the needle is withdrawn from the vial opening and the intravenous connector tube is inserted in the vial opening. The person performing the procedure must pull the needle from the sheath and vial with one hand and discard it while keeping the sheath properly in place in the vein by holding the vial on the sheath with the other hand. During that interim blood back-flows outwardly from the vein through the sheath into the vial and thence through the vial opening. It is the principal purpose of the present invention to modify this conventional method of intravenous injection and apparatus therefor so that blood back-flowing into the vial after the needle is removed cannot proceed further and all leakage of blood from the vial prior to introduction of the intravenous fluid is prevented.
Some but certainly not all of the components of the catheter of the present invention which achieve this purpose are disclosed in my prior Pat. No. Design 336,334 issued Jun. 8, 1993. It will be seen from the description below that use of a self-sealing pierced elastomeric diaphragm is part of the present solution in achieving these objectives. Self-sealing elements as such are known in the medical field, as for example the hemostasis valve described in U.S. Pat. No. 4,626,245 and the pierced resealable seal described in U.S. Pat. No. 4,950,260. Neither of those references, however, and as far as is known no other prior art references, disclose the use of a pierced resealable elastomeric diaphragm in conjunction with a needle on a transparent intravenous push-pull element with the diaphragm located over an opening in an intravenous vial and with a vial port separate from that vial opening for connection to a source of intravenous fluid. A side port is associated with the resealable valve of U.S. Pat. No. 4,626,245 but not for introduction of intravenous fluid. This is true also of a side port described in U.S. Pat. No. 5,021,044.